• A.Δz=dz<br/>
• B.<img src="https://timg.fentiku.com/javaimportItems/b402ff216b2d4c2bbebdb4f22b7e3ae8/images/14e4d4.png"><br/>
• C.<img src="https://timg.fentiku.com/javaimportItems/b402ff216b2d4c2bbebdb4f22b7e3ae8/images/151156.png"><br/>
• D.<img src="https://timg.fentiku.com/javaimportItems/b402ff216b2d4c2bbebdb4f22b7e3ae8/images/153ce8.png"><br/>

正确答案：D